After talking with my dad and searching on the internet some, it seems like changing your automatic transmission fluid could ruin your transmission (it slips and won't shift?). Has anyone ever experienced this? From what I've read it mostly happens to vehicles that have a lot of miles on them and have not been serviced at the right intervals (my jeep. the PO didn't take care of it at all).

It's a '99, which I believe has the 32rh in it. 3-speed, no overdrive.

I have 114k miles on mine, and i'm mostly sure the AT fluid hasn't been changed. Ever.
So, has anyone heard that it's a bad idea to change it? Also:
-Why are quick-lube type places and their tranny flushes frowned on?
-How hot does the 32rh run? On average?
-Is it worth my time and money doing it at home?
-It shifts hard. Could this be helped by new fluid?
-How important is changing the transfer case fluid? because that has probably never been done either...

As a side note, I have the carpets out, and the transmission heats up the floorboard to a point that it feels like a space heater on my legs. Maybe not a bad thing in winter, but now in summer, the AC can't even cool the whole jeep down. I do have a hard top and full doors.
Are there any other ways to block the heat aside from putting the carpets back in?

any help is appreciated, I really don't want to kill my transmission with new fluid.

I just had the trans flushed on my 4 runner because the radiator busted and the atf and engine coolant decided to merge. Trans has 145,000 miles and it would barely shift. Had it done at the Dealership for $159 and now it shifts better than it did before. Maybe I got lucky but if decide to go the flushing route I would stay away from the quick lube places...no exp with those places just hear some of the horror stories from others that have had it done at those places. I dont usually go to the dealer but I was actually impressed because I watched him do the flush and he went through about 18 qts of fluid.

thats the stupidiest thing i've heard today. make sure to use the correct transmission fluid and you'll be fine. Use ATF4+ ONLY. Your 32RH could use ATF3+, but they dont make it anymore...ATF4+ took its place.

dropping the pan and refilling the tranny only gets 1/3 the fluid, a full flush is needed to get the fluid in the torque converter. When getting it done at a shop, make sure they used Valvoline or Mopar ATF4+, not some generic tranny fluid, GM Dextron or whatever other crap they're trying to BS off on you. unless you have something already wrong with the tranny...but thats not the fluid's problem.

At 114k miles, if you've never changed the fluid in it, now would be a bad time to start. Even though your fluid is old and might not even look the way its supposed to, brand new fluid will have too many powerful cleaning agents that can deteriorate your transmission. I flushed my 32rh once (about 75k at the time) and got lucky, everything was fine. But when I did it a second time a few months later, I could feel the shifting getting worse immediately after, until I was left driving only in 1st gear. It did get better in the 7 months that I've been driving in this condition, but I'm convinced another flush and I would have to overhaul.

Now I'm no expert but I have experienced this first hand, and have heard of flushes doing more bad than good (when it comes to older cars with a lot of miles), from a ton of friends, mechanics, etc. There is always the possiblilty that you'll flush it and everything will be fine, but my advice would be if its fine the way it is, don't mess with it. If I knew what I was getting myself into, I would've left the dirty, brown fluid in there because it shifted much better with that then it does now with new fluid. Good luck man.

I have also heard from numerous friends that are mechanics that flushing is not good for the trans. The bands adjust to the crap in the fluid and when you flush all the "crap" that was in there that was helping your trans shift properly are now gone. My 32rh just crapped out and is at the trans shop right now getting a rebuild and breather mod

Sometimes when your tranny is starting to slip you notice the fluid is burnt...and sometimes the particles in the burnt fluid are keeping your tranny alive.

if the fluid is burnt, you've likely already done unrepairable damage. if you find parts floating in the pan and large ferrous material stuck to the magnet, you've already done unrepairable damage. its not the new fluid that killed your tranny, its the damage already done.

if the fluid is burnt, you've likely already done unrepairable damage. if you find parts floating in the pan and large ferrous material stuck to the magnet, you've already done unrepairable damage. its not the new fluid that killed your tranny, its the damage already done.

100% agree with you. But you can usually limp by for another good bit of time on that burnt fluid...once you change it, the trans usually goes shortly after.

With that being said I recently changed the fluid on my moms 99 with the 32rh. The fluid was nice and red.

if the fluid is burnt, you've likely already done unrepairable damage. if you find parts floating in the pan and large ferrous material stuck to the magnet, you've already done unrepairable damage. its not the new fluid that killed your tranny, its the damage already done.

100% correct.I have never seen a flush damage a trans,it will however show the damage already done from being neglected.

If you wait that long your trans is doomed either way.ATF+3 and DEXIII are toast at about 30,000 miles,and anytime the fluid temps get above 200 degrees both of those ATF's are done and only causing damage to your trans.

ATF+4 and DEXVI can go longer(60k) but the same rules apply with heat.If you overheat your engine better plan on doing a trans flush also or risk damaging your trans.

It may seem a waste of money but I flush my trans every 15,000 miles(filter change every other flush) and use the correct fluid,but in over 20 years of driving I have never had a trans failure and I'm hard on vehicles(very hard).

I agree with everyone if its brown leave it alone still red go for it. My 99 TJ has 150000+ on it the fluid looks good so I'm going to do mine soon. The person before me ether took care of it or I think it was replaced.

After reading some of the drivel posted in this thread, I feel that I have to comment.

You never ever want to power flush any transmission such as they do at those lube shops withthe machine. That is what can damage internals.

What you want to do is perform a complete fluid exchange. You can set this up where the transmission will do the work for you using its own pump if you know what you are doing or else any reputable tranny shop can do it.

Old fluid and old clogged filters will only serve to ruin your transmission....ATF has a useful life and it is affected dramatically by operating temps. If the tranny was ever overheated or consistently run above 200*, that will impact the service life of the fluid.... cutting it upwards of half if not more.

If your tranny is done, then its done... its not the fluid replacement that will do it in.

I have 115k on my original 32RH and it shifts/drives/performs as if it were new. I do a complete fluid and filter exchange every 15-20K. I'd rather pay for ATF than a new transmission and the 32RH is very tough and dependable if properly maintained.

I posted this yesterday in another trans help thread...This seems like another good spot to say it...

"If your not sure you can do it yourself, then take it to a shop. I do my own stuff...its not that hard really.
The best way to get 99% of the fluid out is to find the output cooler line from the trans.
Disconnect it at the radiator and add a short piece of hose to drain into a bucket.
Start the jeep with the E-brake on and pull the shifter thru all the gears while a helper watches the stream of fluid draining into the bucket. When that stream sputters a bit shut the motor off and put it in park.
At this point its optional to pull the pan and replace the filter, but after a suspected dunk in water, I'd pull the pan and replace the filter. Since you've used the trans pump to pump most of the fluid out, this will be a lot less messy than removing a full pan.
Get a quality filter and a new rubber pan gasket, clean up the inside of the pan, and re-install the pan.
Pour in about 3 qts of new fluid or until you see full or just above on the dipstick.
Start the motor again and have the helper watch the hose. When it sputters, stop the motor and do the fill, pump, watch the hose thing one more time.
When you have decided that your seeing clean fuid being pumped from the hose, stop the motor.
At this time you may want to disconnect the return line at the radiator and let it and the return drain out as much as possible, but the pump should have already returned that contaminated fluid back during your flushing.
Now, hook all your lines back up, top off the fluid level in the pan and you're done. Be sure to check the level after a trip around the block.

I have done my trans flushes this way for years on my F350, TJ, and other cars without issue. All you are doing is using the trans pump to pump out old fluid out the hose while at the same time circulating new fluid throughout the trans. Nothing really different than what the shop does with its flush machine. A case of ATF-4 is sufficent to do the job easily. "

I agree about the powerflush. Depending on the trans after I change the filter I usually pull the hose off the radiator cooler or wherever available while an assistant adds fluid at roughly the same speed.

If its burnt and had over 100k with no changes I suction out 20oz, throw a bottle of lubegard red at it and call it a day.